Prenatal diagnosis of a fetus with trisomy 9 mosaicism

Background Trisomy 9 is a rare chromosomal disorder[1, 2]. Complete trisomy 9 is often fatal, and chromosome 9 mosaicism is commonly observed in clinical practice. Patients with this mosaicism mainly present with "ball nose", microphthalmia, limb dislocation, and other skeletal, cardiac, urogenital and central nervous system malformations.[3]. Case presentation Chromosomal karyotype analysis, chromosomal microarray analysis and fluorescence in situ hybridization analysis were used for the diagnosis of a case of trisomy 9 mosaicism, and a variety of genetic testing techniques were further used for detailed analysis. Conclusion We report a rare case of trisomy 9 mosaicism; fewer than five comparable cases have been reported in the literature. This case highlights the importance of genetic counseling and appropriate genetic testing for prenatal diagnosis.